JP2707186B2 - Combustion equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion apparatus for incinerating municipal garbage and industrial waste, which can prevent generation of trace amounts of harmful substances such as dioxin and can burn with high combustion efficiency. It is about.

[0002]

2. Description of the Related Art In recent years, with the diversification of distribution systems and the like, plastics, fibers, papers, and the like have increased in urban garbage, and urban garbage has a tendency to gradually increase in calories. During the incineration process, plastics may damage refractory materials due to local high-temperature heat generation, clinker may occur, and prevent continuous operation of the furnace and incineration of the rated amount of garbage. . However, it is difficult to completely separate the plastics from the garbage, and if the separated plastics are to be landfilled, a valuable energy source will be landfilled.

[0003] As a combustion device for municipal refuse having a high calorie, a combustion device provided with a fluidized-bed furnace has attracted attention.

[0004]

The combustion mechanism of solid matter is as follows.
The combustion is completed through a water evaporation / drying step, a solid pyrolysis step, and a combustion step of a pyrolysis gas and generated char. In the case of a fluidized-bed furnace, the evaporation and drying of the water and the pyrolysis of the solids are performed within a short period of time. Therefore, in the case of incineration of municipal garbage having inconsistent properties, the amount of generated gas varies. For this reason, the residence time of the combustible gas in the furnace is temporarily reduced. As a result, a small amount of unburned components is generated. In particular, it is remarkable in a medium-sized or smaller plant.

[0005] On the other hand, in the conventional fluidized bed furnace, two-stage combustion is performed. Even in the two-stage combustion, the remaining amount of combustion air is supplied to the freeboard portion, so that there is a limit in reducing NOx.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and provides a combustion apparatus with high combustion efficiency which can completely burn a small amount of unburned components contained in flue gas and achieve low NOx. With the goal.

[0007]

In order to solve the above-mentioned problems, an invention according to claim 1 is a combustion apparatus for charging an incinerated material and burning the incinerated material, wherein a fluid for flowing a fluid medium is provided. A bed and a high temperature oxidizing atmosphere located above the fluidized bed
It is characterized by comprising a freeboard portion of the air and a post-combustion region which is a high-temperature region connected to the freeboard portion via a connection portion.

[0008] The invention according to claim 2 is based on claim 1.
In the combustion device described in the above, the cross-sectional area A at the post-combustion region entrance portion at the connection portion between the freeboard portion and the post-combustion region
_B and the cross-sectional area _{AF at the} free board portion satisfy the following expression. A _F / A _B ≧ 2.5

[0009] The invention described in claim 3 is claim 1 or claim 2.
Is the combustion device according to item 2 , wherein the combustion
It is characterized in that tertiary air for burning unburned gas components is supplied so as to mix and stir the burning gas .

According to a fourth aspect of the present invention, in the combustion apparatus according to any one of the first to third aspects, a large number of pipes having air injection holes in a free board portion are vertically arranged. It is characterized in that a mixing and stirring means having an arrangement is provided.

[0011] Further, the invention according to claim 5 is based on claim 1.
The combustion apparatus according to any one of Items 4 to 4, wherein the fluidized bed portion
Is characterized in that the amount of primary air blown from the bottom of the fluidized bed is equal to or less than the theoretical amount of air, and the fluidized bed performs slow partial combustion of combustion products.

The invention according to claim 6 is the first invention.
In a combustion device according to any one of Itaru 5, freeboard section for burning blow the secondary air, the air ratio from 0.1 to 1.5
In this case, a high-temperature oxidizing atmosphere is used, and tertiary air is blown into the post-combustion region inlet to make the air ratio in the post-combustion region 1.5 or more.

[0013]

According to the first aspect of the present invention, the combustion apparatus is provided with a fluidized bed section.
Since it is composed of a free board section and a post-combustion area, the fluidized bed section
And the free board to form a high-temperature oxidizing atmosphere.
Combustion gas discharged from the oxidizing atmosphere will be
The residence time can be taken, and the fine gas contained in the combustion gas
After that, the amount of the unburned components is completely burnt in the combustion zone,
NOx reduction while at the same time improving combustion efficiency
You.

According to a second aspect of the present invention, there is provided a post-combustion region of a connecting portion.
In cross-sectional area A _B and freeboard section in the band inlet
Since the relationship of the cross-sectional area _AF was set to A _F / A _B ≧ 2.5, the fuel
The mixing and agitation of the burning gas is promoted, and the combustion efficiency is further improved
I do.

According to a third aspect of the present invention, there is provided an after-combustion zone inlet.
Supply tertiary air to the combustion gas in the post-combustion zone.
Mixing and stirring are promoted, and the combustion efficiency is further improved. Ma
According to a fourth aspect of the present invention, an air injection hole is provided in the free board portion.
Mixing and stirring means configured by arranging a large number of pipes having
Promotes mixing and agitation of combustion gas in the freeboard section.
As a result, the combustion efficiency is improved.

[0016] The invention according to claim 6 is a freeboard.
Because the air ratio is small, the cooling effect due to excess air can be reduced.
High temperature in the free board part,
As a result, the combustion efficiency is improved. In addition, the air supply is primary air,
Secondary air, by performing divided into three stages of the tertiary air,
Low NOx can be achieved.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a view showing the structure of the combustion apparatus of the present invention.
1A is a longitudinal sectional view, and FIG. 1B is a side view as viewed from the direction of arrow A. The present combustion apparatus uses a fluidized bed 1 surrounded by furnace walls.
And a freeboard section 2 located above the post-combustion section and a post-combustion area 3 which is a high-temperature area for burning unburned gas components. Further, the connecting portion 4 between the freeboard portion 2 and the post-combustion region is formed to be eccentric with respect to the freeboard portion 2 for the purpose of promoting mixing and stirring of the combustion exhaust gas. The average residence time of the combustion exhaust gas is set in the range of 2 to 4 seconds in the freeboard section 2 and in the range of 1 to 3 seconds in the post-combustion zone 3 and the connection section 4.

A wind box 5 for supplying primary air 7 is provided at the bottom of the fluidized bed 1, and a fluidized bed is formed at the top of the wind box 5. The furnace wall 6 of the free board section 2 is provided with secondary air supply ports 8 and 9. At the connecting portion 4 between the free board portion 2 and the post-combustion region 3, the post-combustion region 3
The cross-sectional area A _F in the cross-sectional area A _B and freeboard section 2 at the inlet portion is adapted to satisfy the following equation. A _F / A _B ≧ 2.5

Further, a dust supply port 10 is provided in the furnace wall 6 of the free board section 2. Further, a tertiary air supply port 11 is provided at an inlet portion of the post-combustion zone 3. By supplying tertiary air from the tertiary air supply port 11, mixing and stirring of the combustion gas is performed. The upper part of the post-combustion zone 3 is connected to the exhaust gas outlet 12. Hereinafter, the operation of the combustion device having the above structure will be described.

As described above, the combustion of the solid material includes (1) a step of evaporating and drying water, (2) a thermal decomposition step of the solid matter,
(3) The combustion is completed through the combustion process of the pyrolysis product gas and the generated char. The refuse is supplied from the refuse supply port 10 into the fluidized medium (sand) of the fluidized bed 1 having a high and uniform temperature. The flammable substances contained in the garbage are as described in (1),
Since the three steps (2) and (3) are performed, there is no flammable substance in the residue discharged from the bottom of the fluidized bed 1.

However, since the above two steps (1) and (2) are performed in a short time, in the case of municipal garbage whose properties are not constant, it appears as fluctuations in the generated gas. As a result, the oxygen concentration required for combustion in the furnace fluctuates. That is, there arises a problem that the combustion air (oxygen) becomes excessive and the combustion temperature decreases, and conversely, oxygen becomes insufficient and is discharged to the atmosphere unburned. Furthermore, the distribution of oxygen in the furnace becomes non-uniform due to the furnace shape and gas mixing, and as a result, unburned components are contained in the exhaust gas.

In order to solve this problem, in the present combustion apparatus,
A post-combustion region 3 is provided above the free board 2.
By providing the post-combustion zone 3, (1) a rectifying action at the inlet, (2) a mixing action by tertiary air inflow from the tertiary air supply port 11 at the inlet, and (3) a post-combustion in the high-temperature zone. By ensuring the exhaust gas residence time in the region 3, diffusion combustion action can be expected.

The present combustion apparatus divides a high-temperature region (combustion region) into three regions, a fluidized bed portion 1, a freeboard portion 2, and a post-combustion region 3, and operates with respective roles. The operating condition standards in each of the fluidized bed section 1, the freeboard section 2, and the post-combustion zone 3 are set as follows.

(1) Criteria for Setting Temperature Range a) The temperature of the fluidized bed 1 is preferably low in order to make the gasification rate of refuse slower, and the upper limit is set to 700 ° C. in this embodiment. . On the other hand, the lower limit is governed by the gasification temperature of the substances that make up the municipal solid waste. Gasification is complete,
It is important that the burning loss of incombustibles is extremely small.
Most of the pyrolysis temperatures of materials constituting municipal waste such as paper and plastic are 400 ° C. or less, and in this embodiment, the lower limit was set to 600 ° C. in consideration of a sufficient margin. b) The upper limits of the temperatures of the freeboard section 2 and the post-combustion zone 3 were set to 950 ° C. in order to suppress the generation of thermal NOx and to prevent the dust problem due to fly ash. On the other hand, the lower limit was set to 800 ° C. or higher in order to ensure a good combustion state.

(2) Criteria for setting air ratio a) Air ratio of fluidized bed 1 {supply air amount: minimum air amount (theoretical air amount) required for combustion of combustion products}, that is, from the bottom of fluidized bed unit 1 The upper limit of the amount of primary air to be blown was set to an air ratio of 1 or less in order to perform partial combustion of dust. On the other hand, the lower limit is set to the amount of air necessary to fluidize the fluid medium. b) The air ratio of the free board section 2 enables high-temperature combustion, and at the same time, the air ratio is 1.0 to 1.
The high temperature oxidizing atmosphere in the region of No. 5 was set. c) The air ratio in the post-combustion region 3 is an amount necessary for completing the combustion of a small amount of unburned components, and by blowing tertiary air from the tertiary air supply port 11 at the inlet of the post-combustion region 3, The air ratio in the combustion zone 3 is set to 1.5 or more.

Preheating of secondary air and tertiary air The secondary air and tertiary air supplied from the secondary air supply ports 8 and 9 and the tertiary air supply port 11 have a function of maintaining temperature and agitating in order to complete combustion efficiently. It needs to be done. In this embodiment, the secondary air supply ports 8 and 9 and the tertiary air supply port 1
By preheating the secondary air and tertiary air supplied from 1, the inside of the freeboard section 2 and the post-combustion zone 3 were heated, and the combustion gas was stirred by the secondary air and tertiary air. In addition, by preheating the secondary air, high-temperature combustion is possible even with low-calorific value garbage, and overcooling by secondary air due to fluctuations in the amount of combustion gas due to fluctuations in the garbage supply and fluctuations in the properties of the garbage are prevented. And stable combustion can be ensured.

FIG. 2 is a view showing another structure of the combustion apparatus of the present invention. FIG. 2 (A) is a longitudinal sectional view, and FIG. 2 (B) is a side view as viewed from the direction of arrow A. This combustion apparatus is composed of a fluidized bed section 1 surrounded by furnace walls, a freeboard section 2 located above the bed section 1, and a post-combustion section 3 which is a high-temperature area for burning unburned components. It is the same as that of the combustion device. This combustion apparatus differs from the combustion apparatus of FIG. 1 in that a large number of pipes 13 having air injection holes in the freeboard section 2 are illustrated.
The point is that they are arranged vertically . Mixing and stirring action of the combustion gases in the by re freeboard section 2 in this improved. What
In addition, many pipes 13 are supplied from the secondary air supply ports 8 and 9
Secondary air that performs the same function as the secondary air
Even if it branches off from a blower that sends primary and secondary air (not shown)
Alternatively, a dedicated blower may be used. The pipe 13
The amount of secondary air increases by the amount of air injected from the
The air ratio of the lead board portion 2 increases.

[0028]

According to the present invention, as described in detail above, the following excellent effects can be expected. (1) According to the first aspect of the present invention, since the combustion device is constituted by the fluidized bed, the freeboard section in the high-temperature oxidizing atmosphere, and the post-combustion region, the combustion gas discharged from the freeboard section in the high-temperature oxidizing atmosphere is high in temperature A sufficient residence time can be taken in the post-combustion region, which is a region, and a small amount of unburned components contained in the combustion gas completely burns in the post-combustion region, and the combustion efficiency of the unburned components is improved. Low NOx can be achieved. (2) According to the second aspect of the present invention, since the relationship between the cross-sectional area A _F in the cross-sectional area A _B and freeboard section in the combustion zone inlet after the connecting portion was set to A _{F /} A _B ≧ 2.5 In addition, the mixing and stirring of the combustion gas is promoted, and the combustion efficiency is further improved. (3) According to the third aspect of the present invention, since the tertiary air is supplied to the inlet portion of the post-combustion region, the mixing and stirring of the combustion gas in the post-combustion region is promoted, and the combustion efficiency is further improved. (4) According to the fourth aspect of the present invention, the mixing / stirring means configured by arranging a large number of pipes having air injection holes in the freeboard portion facilitates mixing and stirring of the combustion gas in the freeboard portion, and burns. Efficiency is improved. (5) In the invention according to claim 6, since the air ratio at the free board is small, the cooling effect due to excess air can be reduced.
It is possible to raise the temperature in the free board portion, and as a result, the combustion efficiency is improved. Furthermore, by performing air supply in three stages of primary air, secondary air, and tertiary air, low NO
x conversion can be achieved.

[Brief description of the drawings]

FIG. 1 is a view showing the structure of a combustion apparatus according to the present invention;
1A is a longitudinal sectional view, and FIG. 1B is a side view as viewed from the direction of arrow A.

FIG. 2 is a view showing another structure of the combustion apparatus of the present invention.
2A is a longitudinal sectional view, and FIG. 2B is a side view as viewed from the direction of arrow A.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fluidized bed part 2 Free board part 3 Post-combustion area 4 Connection part 5 Wind box 6 Furnace wall 7 Primary air 8 Secondary air supply port 9 Secondary air supply port 10 Garbage supply port 11 Tertiary air supply port 12 Exhaust gas discharge port 13 Pipe with air injection holes

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Mitsutoshi Yamamoto 11-1 Haneda Asahimachi, Ota-ku, Tokyo Ebara Corporation (56) References JP-A-3-271610 (JP, A) JP JP-A-63-279013 (JP, A) JP-A-58-156107 (JP, A) JP-A-2-12429 (JP, Y2) JP-A-51-38719 (JP, Y2) JP-A-49-44304 (JP, A) , Y2)

Claims (6)

(57) [Claims] 1. A combustion device for charging an incinerated material and burning the incinerated material, comprising: a fluidized bed section for flowing a fluidized medium; and a freeboard section in a high-temperature oxidizing atmosphere located above the fluidized bed. And a post-combustion region which is a high-temperature region connected to the freeboard portion via a connection portion. 2. A connecting portion of the freeboard section and post-combustion region, claim the cross-sectional area A _F in the cross-sectional area A _B and freeboard section in the post combustion zone inlet is characterized by satisfying the following equation 2. The combustion device according to 1. A _F / A _B ≧ 2.5 3. A combustion gas is mixed into the post-combustion zone inlet.
The combustion device according to claim 1 or 2 , wherein tertiary air for burning unburned gas components is supplied so as to be stirred . 4. A mixing / stirring means having a structure in which a number of pipes having air injection holes are vertically arranged in said free board portion. Combustion equipment. 5. The fluidized bed according to claim 1, wherein the amount of primary air blown from the bottom of the fluidized bed is less than or equal to the theoretical amount of air, and the fluidized bed performs slow partial combustion of combustion products. A combustion device according to any one of the preceding claims. 6. A secondary air is blown into the free board portion, a high-temperature oxidizing atmosphere is set at an air ratio of 1.0 to 1.5, and tertiary air is further blown into the post-combustion zone inlet. 6. The combustion device according to claim 3, wherein the air ratio in the combustion region is 1.5 or more.